A Three-Port Coupled Resonator Decoupling Network for Mutual Coupling Reduction of Three-Element Antenna Arrays

A new decoupling scheme named three-port coupled resonator decoupling network (CRDN) is proposed. The matching and decoupling conditions for the three coupled antennas are proposed, and the decoupling condition for the real part of the mutual admittances between three coupled antennas is derived. More importantly, a comprehensive synthesis theory for the three-port CRDN is proposed. In order to prove this concept, three different configurations of three-element are designed for verification, including not only triangular arrays but also linear antenna arrays. Simulated and measured results show that in all three examples, multiple types of coupling between antennas can be reduced to below <inline-formula> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula>20 dB. Furthermore, the total efficiency and envelope correlation coefficient of the decoupled antennas are significantly improved compared with the coupled counterparts. The proposed three-port CRDN is easy to implement and is attractive for multiple-input multiple-output (MIMO) applications.